ISSN:
1572-9605
Schlagwort(e):
GdBa2Cu3O7−δ
;
Ca substitution
;
Mo substitution
;
Hf substitution
;
crystal structure
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Elektrotechnik, Elektronik, Nachrichtentechnik
,
Physik
Notizen:
Abstract The structural and superconducting properties of (Gd1−x−y Ca y M x )Ba2Cu3O z with M = Mo, Hf are investigated using X-ray diffraction, electrical resistivity, and oxygen content measurements. The effect of increasing the Mo concentration in (Gd1−x Mo x )Ba2Cu3O z changes the structure from orthorhombic to tetragonal accompanied by a large increase in resistivity and a fast decrease in T c at the rate of 1.9 K per at.% of Mo, unlike that of Hf substitution in (Gd1−x Hf x )Ba2Cu3O z , which maintains the orthorhombic structure and decreases T c very slowly at the rate of 0.6 K per atm.% of Hf with nearly no change in resistivity. The suppression of T c by M = Mo, Hf can be counterbalanced by hole doping by Ca which increases T c with increasing Ca content showing maximum compensation for Mo. A comparative study of M = Mo, Hf doped samples in (Gd1−x−y Ca y M x )Ba2Cu3O z indicates that the valence of the dopant M = Mo4+,6+, Hf4+ and its ionic radius play an important role in controlling the structural and superconducting properties of the systems.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1023/A:1022644203794
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